MUMBAI: Shares of Tata Motors, Tata Steel, Tata Power and other Tata Group companies were in the positive terrain as Ratan Tata's 21-year old reign at the helm of the $100 billion group comes to an end today.

Cyrus Mistry will succeed him as the Chairman of the Group from today.

Lauding the retiring chairman of the group, JJ Irani, Former Director, Tata Sons said, "What Ratan Tata has left behind is that he has taught the group to think big. When he took over, I do not think our combined turnover was even $10 billion. In the last 20 years, it has increased to $100 billion."

"The opportunity was there. He grabbed it and he taught all the companies to think big and most importantly to think beyond the shores of India," he told ET Now.

Under the leadership of Ratan Tata, most Tata Group companies have outperformed the Nifty, which has gained 25 per cent, in year 2012.